Coating composition containing epoxy resin and copolymer of ring-alkylated styrene



United States COATING COMPOSITION CONTAINING EPOXY RESIN AND COPOLYMER OF RING-ALKYL- ATED STYRENE James David Murdock and Gordon Hart Segall, Montee des Trente, Quebec, Canada, assignors to Canadian Industries Limited, Montreal, Quebec, Canada, a corporation of Canada This invention relates to new coating compositions. More particularly, it relates to new coating compositions based on copolymers of alkylated styrenes, acrylic acids and alkyl esters of acrylic acids.

In Canadian Patent No. 534,261, dated December 11, 1956, in the names of G. H. Segall and J. L. Cameron, there are described and claimed coating compositions adapted for being hardened into infusible and solvent insoluble films on baking at a temperature of from 100 to 150 C., the said coating compositions comprising essentially a linear thermoplastic copolymer of from 15 to 80 parts of styrene and from 15 to 80 parts of an alkyl ester of acrylic acid and from 5 to parts of an acrylic acid, the total parts being 100, in admixture with from to 55%, by weight of said copolymer, of a low molecular weight polymeric condensation product of diphenylolpropane with epichlorohydrin, said condensation product having an epoxide content of at least 7.5% by weight and a melting point not exceeding 75 C., and a Gardner viscosity not exceeding 1.65 poises as a 40% solution in ethylene glycol monobutyl ether, and from 0.5 to 2.0% by weight of said copolymer and condensation product jointly, of a quaternary ammonium hydroxide having at least one alkyl group of from 12 to 18 carbon atoms attached to its nitrogen atom.

Despite their many useful properties, those of the aforesaid coating compositions which contain a copolymer of methyl or ethyl acrylate and styrene and which have more than 50% by weight of styrene, are still objectionable in that they are susceptible to cratering in the presence of contaminants such as alkyd spray dust, which renders them undesirable for use in such locations as electrical appliance finishing shops where a large quantity of coating compositions based on alkyd resins is generally used for finishing purposes.

It has now been found that if in the aforesaid objectionable coating compositions the styrene of the copolymer is replaced by an alkylated styrene, compositions are obtained which not only possess all the desirable properties of the compositions containing a styrene copolymer but also, and unexpectedly, withstand cratering in the presence of alkyd spray particles.

It has, moreover, been found that in these aforesaid objectionable coating compositions, the lower alkyl esters of acrylic acid of the copolymers may be replaced wholly or in part by the equivalent esters of methacrylic acid, provided always that the styrene portion of the copolymer has been replaced by an alkylated styrene.

It is. therefore an object of this invention to provide new coating compositions.

Another object of this invention is to provide new coating compositions based on copolymers of alkylated styrens, acrylic or methacrylic acids and alkyl esters of acrylic or methacrylic acids. 1

A further object of this invention is to provide coating compositions as hereinbefore defined which are" un- 2,964,492 Patented Dec. 13, 1960 will become apparent hereinafter.

The new coating compositions of the invention com-- prise essentially a linear thermoplastic copolymer of more:

than 50 parts of an alkylated styrene and at least 15 parts: of methyl or ethyl acrylate or methacrylate and from 2 to 14 parts of acrylic or methacrylic acid, the total parts: being 100, in admixture with from 15 to 55%, by weight of the copolymer, of a low molecular weight polymeric:- condensation product of diphenylolpropane with epichlo-- rohydrin, said condensation product having an epoxide: content of at least 7.5 by weight and a melting point not; exceeding C., and a Gardner viscosity not exceeding: 1.65 poises as a 40% solution in ethylene glycol monobutyl ether, and from 0.5% to 5.0% by weight of said copolymer and condensation product jointly, of a catalyst; selected from the group consisting of amines and quater-- at least one alkyl group of from 12 to 18 carbon atoms attached to the nitrogen atom. These coating compositions are resistant to cratering in the presence of contaminants and yield,

upon baking at a temperature of from to C., protective coating films equal in quality to those obtained from analogous prior art compositions in the absence contaminants.

The details and manner of practising this invention i will be apparent by reference to the following specific examples wherein the parts given are by weight, it being understood that these examples are merely illustrative embodiments of the invention and that the scope of the invention is not limited thereto.

Example I To 100 parts of a solution containing 26 parts of a copolymer of 72 parts of vinyl toluene, 20 parts of ethyl acrylate and 8 parts of acrylic acid, 33 parts of titanium dioxide pigment and 41 parts of a mixture of butanol,

xylene and toluene, there were added 39 parts of a solu-' tion containing 17.6 parts of butyl acetate, 12.4 parts of ethyl acetate, 1.2 parts of octadecyl trimethyl ammonium hydroxide and 7.8 parts of a polymeric diphenylolpropane/epichlorohydrin condensation product, said conden sation product having an epoxide content of 7.58.5% by Weight and a melting point of 6575 C., and a Gard- 40% solution in The total non-volatile material of the resultant solution was then adjusted to ner viscosity of 0.85-1.65 poises as a ethylene glycol monobutyl ether.

44% by the addition of xylene.

This solution was then sprayed on three steel panels, A

the first of which had of alkyd enamel.

and the third one, of alkyd enamel. All three baked for 30 minutes at 150 found that none of the baked films displayed any cratermg. insoluble.

previously received a short spray The first two panels were then removed Theresults recorded above were not materially changed with a similarly constituted solution containing, however, a copolymer in which the 20 parts of-ethyl acrylate had been replaced 'by 20 parts of methyl 'methac rylate or-20- trating the efiiciency of the vinyl toluene'i'n mer in preventing cratering of the paint film.

while still wet, received a short spray panels were subsequently C. after which time it was All films were, of course, infusible and solventacrylic acidjcopolym er resulted in crater ing of the first and third panels, thus illus-- the COPOIY': I

Frazier, dated February128; 1956,- 1.1 partsof. octadecyl trimethyl ammoniumhydroxideand 7.4 parts of thepolymeric diphcnylolpropanewepichlorohydrin; condensationproduct described in Example 1.. The total non-volatile material of the resultant-solution was then. adjusted to 44% by the addition of further aliphatic-aromatic solvent.

.A, steel panel was then-sprayedwith the. solution, and, while still wet, shortly sprayedxwith alkyd enamel. After baking the panel for 30 minutes. at 150 C'., there. wasno evidence of cratering" of the. infusible and solvent-insoluble protective coating film.

Example III 100 parts of a solution-containing, 18 parts of acopolymer of 72 parts of p-isopropyl styrene, parts ethyl acrylate and 8 partsof acrylic acid, 40' parts of titanium dioxide pigment and 42 parts of a mixture of xylene, tolu one and butanol, were mixed with 17 parts of a solution:

containing 3. parts. of octadecyl trimethyl ammonium hydri'oxide, 7 parts o the polymeric diphenylolpropane/ epichlorohydrin condensation product described in Ex-- ample. I and 7 parts: of butyl-acetate-ethyl acetate solvent, and the resultantsolution was diluted to 47% total solids by further addition. of xylene.

A. steel panel sprayed. withthe solution, over-sprayed withfalkyd enamel and baked at 150? C. for minutes showed no cratering of theinsoluble: and infusible protective coating film.

Exam pic I V" Results comparable to those obtained in the previous examples-wereobtained'by carrying out similar experiments using copolymers of the following, compositions:

Vinyl Methyl Ethyl Acrylic Metha- Tolucne, Methac Acrylate,- Acid, crylic percent rylate, percent; percent Acid,

percent. percent Example V Lack of crateringof baked films;v was .also observed by conducting experiments similar to those. of the previous examples but using thefollowing baking catalysts instead or octadecyl trimethyl ammonium hydroxide:

('a) A tertiary amine having one methyl group and two longchainhydrocarbon groups from coconut fatty acids.

(b) A tertiary amine having one methyl group and two long chain-hydrocarbon groups from soya 'fatty acids.

((2)11 A .--..tertiar.y aminehavingone "methyl group and twm longyrchainchydrocarbon groupsafr'om'. hydrogenated tallow fatty acids.

(d.) ..,A:te11tiary amine-'havingiwo methyl groups. and'one long ehain hydrocarbon, group: from. cocom1t fattyacid.

(at): tertiary aminezhav-ing two methyl groupsand one; long. chaimhydrocatbcn-group from-pahnitie; fatty:

acid? (f) A tertiary amine having two methyl groups and one long chain hydrocarbon group from hydrogenated tallow fatty acids.

(g) A tertiary amine having two methyl groups and one long chain hydrocarbon group from stearic fatty acid. (12) A secondary amine having two groups derived from coconut fatty acids.

(1') A primary amine derived "from" soya fatty'aci'ds. (j) A diamine, one amino group" being primary the other secondary, the alkyl group of the secondary amino group being derived from soya fatty'acids.

(k) A primary amine derived'from ta-llow-fat ty acids. The above-detailed examples illustrate certain embodiments of the invention wherein there are prepared and may be present in the coatingcomposi-tions in amounts ranging from 0.5 to 5% by weight of the copolymer and condensation product jointly.

For the preparation of the copolymers', any of the wellknown processes for thecopolymerization of styrene can beused.

In the foregoing examples, titanium dioxide is used" as the pigment constituent of the coating compositions. Other pigments may also be used either alone or in admixture to produce enamels of various colours. These enamels are, however, of particular value when produced with white pigments since they are highly resistant to yellowing on baking.

The embodiments of the invention in which an exc1u-.

sive property or privilege is claimed are defined as follows:

1. A coating composition which comprises essentially a linear thermoplastic copolymerof more than 50 parts of a ring-alkylated styreneand at least 15 parts of a member selectedfrom the group consisting of methyl and ethyl acrylates. and. methyl and ethyl methacrylates, and from 2 to 14 parts of a member selected from the group corisisting of acrylic and methacrylic acid, the total parts being 100, in admixture with from 15% to 55%, by weight of the copolymer, of a low molecular weight polymeric condensation'product of diphenylolpropane with epichlorohydrin, said condensation product having an epoxide content of at least 7.5% by weight and a melting point not exceeding C., and a Gardner viscosity not exceeding 1.65 poises as .a 40% solution in ethyleneglycol monobutyl ether, and from 0.5% to 5.0% by weight of said polymer and condensation product jointly, of a catalyst selected from the group consisting of amines and quaternary ammonium hydroxides 'having' at least one alkyl group of from 12 to IS -carbon atoms attached to the nitrogen atom.

2. A coating composition as claimed in claim'l wherein the linear thermoplastic copolymer is a copolymer of 72 parts of vinyl toluene, 20 partsof ethyl acrylate and 8 parts of acrylic acid;

3. .A ccatingfcomposition as claimed inclai'm l wherein the linear thermoplastic copolymer'isa copolymerof- 61 parts of vinyl toluene,..29.6. parts of ethyl. acrylate-and 9.4 parts of methacrylic acid.

and 8 partsof acrylicuacida 5 6 5. A coating composition as claimed in claim 1 wherein 2,767,153 Sutton Oct. 16, 1956 the ring-alkylated styrene is selected from the group con- 2,772,166 Fowler Nov. 27, 1956 sisting of vinyl toluene and p-isopropyl styrene. 2,798,861 Segall et al. July 9, 1957 2,916,469 Lal Dec. 8, 1959 References Cited 1n the file of this patent 5 FOREIGN PATENTS UNITED STATES PATENTS 534,261 Canada Dec. 11, 1956 2,736,717 Frazrer Feb. 28, 1956 

1. A COATING COMPOSITION WHICH COMPRISES ESSENTIALLY A LINEAR THERMOPLASTIC COPOLYMER OF MORE THAN 50 PARTS OF A RING-ALKALATED STYRENE AND AT LEAST 15 PARTS OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF METHYL AND ETHYL ACRYLATES AND METHYL AND ETHYL METHACRYLATES, AND FROM 2 TO 14 PARTS OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF ACRYLIC AND METHACRYLIC ACID, THE TOTAL PARTS BEING 100, IN ADMIXTURE WITH FROM 15% TO 55%, BY WEIGHT OF THE COPOLYMER, OF A LOW MOLECULAR WEIGHT POLYMERIC CONDENSATION PRODUCT OF DIPHENYLOLPROPANE WITH EPICHLOROHYDRIN, SAID CONDENSATION PRODUCT HAVING AN EPOXIDE CONTENT OF AT LEAST 7.5% BY WEIGHT AND A MELTING POINT NOT EXCEEDING 75*C., AND A GARDNER VISCOSITY NOT EXCEEDING 1.65 POISES AS A 40% SOLUTION IN ETHYLENE GLY COL MONOBUTYL ETHER, AND FROM 0.5% TO 5.0% BY WEIGHT OF SAID POLYMER AND CONDENSATION PRODUCT JOINTLY, OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF AMINES AND QUATERNARY AMMONIUM HYDROXIDES HAVING AT LEAST ONE ALKYL GROUP OF FROM 12 TO 18 CARBON ATOMS ATTACHED TO THE NITROGEN ATOM. 